Storms That Surprised Europe Show Forecast Limits

The day before the first of two fierce storms touched down on France's west coast last week, streaking across the country and causing heavy damage in other parts of Europe as well, meteorologists here predicted stormy weather, but nothing out of the ordinary.

There was no warning of the gale-force winds that tore down one-quarter of the country's electric grid, uprooted thousands of trees and damaged some of the country's best known historic monuments, including Notre Dame and Versailles.

A week later, France is still struggling with the damage, with more than 400,000 homes yet to get power back.

So in this age of satellite weather pictures and computer projections, how could these storms have taken a continent so completely by surprise? Are fierce and unpredictable storms part of a new weather pattern related to global warming? Are there more to come?

Experts say that predicting weather in Europe remains particularly difficult, despite the latest technology. Most meteorologists rely heavily on computerized models that must be fed a great number of up-to-the-minute weather observations. The problem is that many of Europe's weather patterns come off the Atlantic Ocean, where observations are sparse. Key factors may not be detected, so the models, never fool-proof, have a greater chance of failing.

''The problem with this storm is that it came like a cannon shot, very fast and very straight, so there wasn't much time to collect anything,'' said Patrick Galois, a forecaster with the French national weather service, Meteo.

''But it's always hard to get good information over the Atlantic. There are boats out there that send wind, temperature and pressure information and we get information from satellites, too, but they look down over what is going on from very high up. We just don't get a good picture of everything going on over the sea.''

Mr. Galois said new satellites to be launched later this year might improve the information that went into forecasting.

Severe fall and winter storms are not rare in Europe, Mr. Galois said. In late October 1987, for instance, a storm with 100-mile winds paralyzed London, killing 13 people and destroying some 1,000 trees at Kew Gardens, the world's oldest and most famous arboretum. In early 1990, storms with hurricane-force winds slashed through Western Europe three times in six weeks, killing more than 140 people and causing perhaps a billion dollars in damage.

But, like other experts, Mr. Galois pointed out that the intensity of the two most recent hurricanelike storms was rare, and that the appearance of two such storms within 48 hours was even more so, a phenomenon seen perhaps once in a century. Mr. Galois said the first storm took a mere 24 hours to cross the Atlantic. Usually, weather patterns take 48 hours.

Whether or not global warming will be a factor in creating more such storms remains an open question. Mr. Galois said not enough information was yet available about what added warmth might touch off.

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''It does not create storms, but maybe it will have an effect on them,'' Mr. Galois said. ''If the oceans are warmer, that could be another source of energy out there that might intensify a storm.''

Some climatologists say that if the atmosphere warms as predicted, storms will become more intense. But while there is some evidence that rainstorms have become heavier in some parts of the world, there is no solid indication of stronger wind storms. At any rate, experts say, no specific weather development can yet be attributed to global climate change.

The two storms that struck Europe beginning Dec. 26 are the kind that develop along a front, or boundary, between cold arctic air and warmer southern air that circles the globe. Above this boundary is the jet stream, the high altitude river of air in which most storm systems are embedded, and that carries them on a general west-to-east course.

In this case, meteorologists say, the jet stream was classically placed and of classic strength to promote the development of superstorms. It was a ''fast, ripsnorting jet stream right straight west to east, across the Atlantic from the U.S. to Europe,'' said Jim Wagner, a meteorologist with the federal Climate Prediction Center at Camp Springs, Md. This is the kind of atmosphere setup that can cause a storm to blossom explosively if one should develop.

The faster the jet stream, the more air it whisks away from the area of a developing storm below it. This further lowers the air pressure within the storms (by taking air away from them). The lower the pressure, the faster air rushes in from outside the storm to try to equalize things. This rush of air is wind, and the lower the storm's pressure, the stronger it is. Relatively warm air off the ocean also imparted extra energy to the system.

Meanwhile, farther south, an unusually strong high-pressure system made the difference between the center of the storm and the outside air even greater, and the winds became even stronger -- in this case, as strong as a moderately severe hurricane. All these factors played a role in producing the winds that did most of the European damage.

The storms themselves were relatively small vortexes of wind and precipitation circling counterclockwise around a central core. It was the sustained winds of these vortexes, much like those that circulate around a hurricane, that blasted the continent. Some tornadoes might have spun off, said Todd Miner, a meteorologist at Pennsylvania State University. But if they did, he said, they were not the major problem.

The first storm hit northern France hardest. The second tore through the southern half of the country. Together they caused perhaps as much as $4 billion worth of damage, according to some insurers, and killed 88 people in France alone.

The national electricity company, EDF, said today that the task of restoring power was proving more difficult than expected and was hampered by bad weather. Fog prevented some helicopters from taking off. Snow and flooding were also making repairs more difficult.

But lack of electricity was not the only problem. The Education Minister, Claude Allegre, announced that about 40 schools would remain closed because of damage when classes resumed on Tuesday after the Christmas and New Year's holiday. About 900 of France's 11,400 schools were damaged by the storms.